Search libraries in GUIX_KF5INIT_LIB_PATH.

Based on an idea by NixOs
pkgs/development/libraries/kde-frameworks/kinit/kinit-libpath.patch

===================================================================
--- kinit-5.32.0/src/kdeinit/kinit.cpp.orig	2017-10-22 21:02:20.908765455 +0200
+++ kinit-5.32.0/src/kdeinit/kinit.cpp	2017-10-22 21:03:25.312818248 +0200
@@ -623,20 +623,18 @@
             if (libpath_relative) {
                 // NB: Because Qt makes the actual dlopen() call, the
                 //     RUNPATH of kdeinit is *not* respected - see
                 //     https://sourceware.org/bugzilla/show_bug.cgi?id=13945
                 //     - so we try hacking it in ourselves
-                QString install_lib_dir = QFile::decodeName(
-                        CMAKE_INSTALL_PREFIX "/" LIB_INSTALL_DIR "/");
-                QString orig_libpath = libpath;
-                libpath = install_lib_dir + libpath;
-                l.setFileName(libpath);
-                if (!l.load()) {
-                    libpath = orig_libpath;
-                    l.setFileName(libpath);
-                    l.load();
-                }
+                // Try to load the library relative to the active profiles.
+                QByteArrayList profiles = qgetenv("KDEINIT5_LIBRARY_PATH").split(':');
+                for (const QByteArray &profile: profiles) {
+                    if (!profile.isEmpty()) {
+                        l.setFileName(QFile::decodeName(profile) + QStringLiteral("/") + libpath);
+                        if (l.load()) break;
+                    }
+		}
             } else {
                 l.load();
             }
             if (!l.isLoaded()) {
                 QString ltdlError(l.errorString());
value='author'>author</option>
<option value='committer'>committer</option>
<option value='range'>range</option>
</select>
<input class='txt' type='search' size='10' name='q' value=''/>
<input type='submit' value='search'/>
</form>
</td></tr></table>
<div class='path'>path: <a href='/guix/log/?id=70a17df684173cc59c19df10e249ac90e1cfb10e'>root</a>/<a href='/guix/log/gnu?id=70a17df684173cc59c19df10e249ac90e1cfb10e'>gnu</a>/<a href='/guix/log/gnu/packages?id=70a17df684173cc59c19df10e249ac90e1cfb10e'>packages</a>/<a href='/guix/log/gnu/packages/tcl.scm?id=70a17df684173cc59c19df10e249ac90e1cfb10e'>tcl.scm</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/gnu/packages/tcl.scm?id=70a17df684173cc59c19df10e249ac90e1cfb10e&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-01-22 22:12:34 +0100'>2020-01-22</span></td><td><a href='/guix/commit/gnu/packages/tcl.scm?id=4bd428a7ce382f623784a3ff8186aadc3cebca91'>gnu: Replace uses of 'libjpeg' with 'libjpeg-turbo'.</a><span class='msg-avail'>...</span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2019-12-19 09:51:56 +0100'>2019-12-19</span></td><td><a href='/guix/commit/gnu/packages/tcl.scm?id=8a0e29d8b9da4a277c8f9613be85df16de9e8898'>gnu: tcl: Fix cross-compilation.</a><span class='msg-avail'>...</span></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2019-12-05 17:59:01 +0100'>2019-12-05</span></td><td><a href='/guix/commit/gnu/packages/tcl.scm?id=72c7788fcf0d619fb5e99c7da0c087af8edbd6bb'>gnu: Tcl/Tk: Update to 8.6.10.</a><span class='msg-avail'>...</span></td><td>Marius Bakke</td></tr>
<tr><td><span title='2019-10-14 10:03:19 +0200'>2019-10-14</span></td><td><a href='/guix/commit/gnu/packages/tcl.scm?id=c206f1914e9299b3f9a8b8be295a02f14acc67b3'>Merge remote-tracking branch 'signed/master' into core-updates</a></td><td>Mathieu Othacehe</td></tr>
<tr><td><span title='2019-10-13 18:35:59 +0200'>2019-10-13</span></td><td><a href='/guix/commit/gnu/packages/tcl.scm?id=068d0a1c345104983a9b43f5e2cf4f7e70ab3c07'>gnu: tcl: Update home page.</a><span class='msg-avail'>...</span></td><td>Marius Bakke</td></tr>